function ll = log_likelihood(data, mu, sigma, lambda)

N = size(data, 1);
K = size(mu, 1);
X = data;
ll = 0;

for i = 1:N
    sum = 0;
    for j = 1:K
        sum = sum + lambda(j)*mvn(X(i,:), mu(j,:), sigma{j});
    end
    ll = ll + log(sum);
end
end


